1. Field
Embodiments of the present invention relate to an electronic brake system, and more particularly, to an electronic brake system capable of a structure simplification and a precise pressure control.
2. Description of the Related Art
A brake system for braking is necessarily mounted on a vehicle, and in recent years, a variety of systems for providing stronger and more stable braking forces have been proposed. For example, there are brake systems such as an anti-lock brake system (ABS) for preventing wheel slid while braking, a brake traction control system (BTCS) for preventing driving wheels from being slipped when a vehicle is suddenly or rapidly accelerated, a vehicle dynamic control system (VDC) for stably maintaining a driving state of a vehicle by combining the ABS with a traction control to control hydraulic pressure of a brake, and the like.
Such an electronic brake system includes multiple solenoid valves for controlling a brake hydraulic pressure delivered to wheel cylinders mounted on wheels of a vehicle, a pair of a low-pressure accumulator and a high-pressure accumulator for temporarily storing oil discharged from the wheel cylinders, a motor and a pump for forcibly pumping oil in the low-pressure accumulator, multiple check valves for preventing a backflow of oil, and an electronic control unit (ECU) for controlling the solenoid valves and a driving of the motor, and these components are compactly installed in a hydraulic block made of aluminum. Also, a hydraulic pressure supply device is provided and used for delivering pressure to the wheel cylinders by receiving a driver's intention to brake in the form of an electrical signal from a pedal displacement sensor that measures a displacement of a brake pedal when the driver steps on the brake pedal.
An electronic brake system provided with such a hydraulic pressure supply device is disclosed in U.S. Patent Laid-open Application Publication No. 2012/0091787. According to the disclosure, the hydraulic pressure supply device is made for operating a motor depending on a pedal effort of a brake pedal to generate a braking pressure. At this time, the braking pressure is generated by converting a rotational force of the motor into a linear motion to press a piston.
However, the electronic brake system with such a structure has a problem that it is difficult to produce a rapid pressure generation and perform a precise control due to a single-acting structure of the hydraulic pressure supply device in which a pressurized piston is returned again to its original position to be operated when a pressure is regenerated or a generated pressure is boosted.
Further, there are problems that multiple valves are required and a passage structure is complicated in order to electronically control the brake system and to perform a variety of functions.